triangular inside circle

Expert replies

[email protected]: Junior | Next Rank: 30 Posts; Posts: 10; Joined: Wed Oct 20, 2010 2:03 am

by [email protected] » Wed Nov 10, 2010 6:51 am

hi everybody got a question see attachment.

I thought asnwer would be 1. because radius is 1, so diameter is 2.
b.h/2=area

so 2.1/2=1?

Attachments

gmatquestion.doc: (65.5 KiB) Downloaded 114 times

Like this post

Source: Beat The GMAT — Problem Solving | Wed Nov 10, 2010 6:51 am

beat_gmat_09: Master | Next Rank: 500 Posts; Posts: 437; Joined: Sat Nov 22, 2008 5:06 amFollowed by: 1 member; Location: India; Thanked: 50 times; GMAT Score:580

by beat_gmat_09 » Wed Nov 10, 2010 7:03 am

[email protected] wrote:hi everybody got a question see attachment.

I thought asnwer would be 1. because radius is 1, so diameter is 2.
b.h/2=area

so 2.1/2=1?

As the diameter of the circle is one of the sides of triangle , triangle is right angled.
D = Hypotenuse = (2*radius) = 2
One of the sides is = 1 i.e. BC =1.
Apply pythagoras therm 2^2 = 1^2 + x^2
THerefore x = (3)^1/2 i.e. sqrt (3).
Base is BC = 1, height is sqrt (3).
Area = BC*sqrt(3)/2 = (sqrt (3)) / 2

Hope is the dream of a man awake

Like this post

Geva@EconomistGMAT: GMAT Instructor; Posts: 905; Joined: Sun Sep 12, 2010 1:38 amFollowed by: 123 members; Thanked: 378 times; GMAT Score:760

by Geva@EconomistGMAT » Wed Nov 10, 2010 7:36 am

beat_gmat_09 gave the correct approach. I'll just nip in and clarify what I think is your own misconception - the height to the diameter is NOT the radius, and is actually shorter than the radius.
A height is a line that originates from a vertex and is perpendicular to the base. If you draw a line form vertex B down to the diameter so that the line is perpendicular to the diamter, the line won't hit the center O (since B is not directly "above" the center, but is more to the right), and thus will not be the radius - a radius is, by definition, a line that connects the center O with a point on the circumference.

to find the area of the triangle, use the two legs of the right angle, which are perpendicular to each other, and can thus act as the base/height of each other.

Geva
Senior Instructor
Master GMAT
1-888-780-GMAT
https://www.mastergmat.com

Like this post

MAAJ: Master | Next Rank: 500 Posts; Posts: 243; Joined: Sun Jul 12, 2009 7:12 amFollowed by: 2 members; Location: Dominican Republic; Thanked: 31 times; GMAT Score:480

by MAAJ » Wed Nov 10, 2010 7:57 am

Other responses to the same question:

https://www.beatthegmat.com/circles-and- ... 31103.html

https://www.beatthegmat.com/gmatprep-que ... 12694.html

You can get these links by writting part of the question stem in the search tool. Hope it helps.

Note: you should read the response from "outreach" quoting:

fleckre wrote:
How do you know triangle ABC is a right triangle?

this is becasue there is a std theorem

"states that if A is any point of the circle with diameter BC (except B or C themselves) ï¿½-ï¿½ABC is a right triangle with A the right angle. The converse states that if a right triangle is inscribed in a circle then the hypotenuse will be a diameter of the circle"

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

559 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review